Steven Runciman in the early 1990s at his home in Dumfriesshire, Scotland.
Photograph: Murdo Macleod for the Guardian

An “alarmingly literate child” by the age of eight, the brilliant Byzantinist Steven Runciman discovered his love of history at Eton (which he loathed) during the first world war. At Cambridge (which he loved) he met Cecil Beaton, whose portrait of Runciman with his pet parakeet, Benedict, is on the book’s cover. Later he taught Guy Burgess at Cambridge. The fastidious Runciman observed that Burgess’s personal hygiene left much to be desired: he often had to “send him away to clean his fingernails”. From the 1930s, Runciman began writing the wide-ranging historical studies for which he is renowned, including a monumental trilogy on the Crusades (1951-54) and The Fall of Constantinople 1453 (1965), which became a bestseller. He was a “playfully elusive figure”, a complex character who could be sparklingly witty yet disliked public speaking and was most happy in private study. At more than 700 pages, Dinshaw’s immense biography offers an evocative and richly detailed portrait of an extraordinary mind and a golden age of scholarship.

•Outlandish Knight: The Byzantine Life of Steven Runciman is published by Penguin. To order a copy for £9.34 (RRP £10.99) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.